The book is quite good at doing the second but not so good at the first. There are descriptions of wall building as well as some material on design however besides mentioning that the walls were breached that's about it for any sort of tactical analysis. We are told at least 20 times that walls are useless militarily this gets rather repetitive after a while. Luckily the history of Chinese exclusivity is quite interesting and provides some nice insights into the Chinese character. A concluding section on Internet censorship seems rather tacked on.